쇄석의 진동다짐 특성에 관한 실험적 고찰

정길수,박병수,홍영길,유남재 江原大學校 産業技術硏究所 2004 産業技術硏究 Vol.24 No.B

This Study is results of experimental works to investigate the characteristics of vibro-compaction of crushed stones having coarse grain sizes. For testing material, crushed stone, sieved within very narrow ranges of grain size distribution, was used. Cyclic loading apparatus was used to apply cyclic loading to the specimen prepared in the mold. Tests were performed by changing the ratio of the maximum to the minimum stress, frequency and the magnitude of the maximum and the minimum stresses. Settlement of specimen due to cyclic loading was measured to analyze the compaction efficiency and sieve analysis test after cyclic loading test was also carried out to find the crushing rate of the specimen. As results of cyclic loading test, normalized settlement in terms of specimen height tends to be converged around loading cycle number of 1500. The magnitude of normalized settlement is in the range of 3.11 ~ 8.57%. The crushing rate is in the range of 4.46 ~ 8.78%. Normalize settlement and the crushing rate tend to increase with decreasing the ratio of the maximum to the minimum stresses and they tend to increase with increasing the frequency and the magnitude of the maximum and the minimum stresses for the given ratio. In conclusions, compaction rate of crushed stone is controlled by the dynamic stress (difference between the maximum and the minimum stresses) and the crushing rate is dominated by applied energy to the specimen.

PBD가 설치된 연약지반의 원심모형실험에 관한 연구

정길수,박병수,전상현,유남재 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.B

This study is the result of experimental and numerical study on the consolidational behavior of multi-layered soft soil ground installed with plastic board drains (PBD). Centrifuge model tests with a marine clay sampled from field were performed to investigate the consolidational behavior of multi layered ground where a dredged soil was placed on the soft clay ground and PBDs were installed. Test results were compared with those of numerical analyses, using the 2-D equivalent model previously proposed. From test resuts, it was found that the amount of consolidation settlement occurred in the original ground due to embankment surcharge loads was in the range of 38% of total settlement in the whole ground. From the results of cone penetration tests executed after finishing the centrifuge model tests, the cone resistance was found to increase with depth. The measured water contents inbetween PBDs were in the ranges of 38~50% and their values tended to increase with increasing the distance between PBDs.

PBD가 설치된 연약지반의 원심모형실험에 관한 연구

정길수,박병수,전상현,유남재 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.A

This study is the results of experimental and numerical study on the consolidational behavior of multi-layered soft soil ground installed with plastic board drains (PBD). Centrifuge model tests with a marine clay sampled from field were performed to investigate the consolidational behavior of multi-layered ground where a dredged soil was placed on the soft clay ground and PBDs were installed. Test results were compared with those of numerical analyses, using the 2-D equivalent model previously proposed. From test resuts, it was found that the amount of consolidation settlement occurred in the original ground due to embankment surcharge loads was in the range of 38% of total settlement in the whole ground. From the results of cone penetration tests executed after finishing the centrifuge model tests, the cone resistance was found to increase with depth. The measured water contents inbetween PBDs were in the ranges of 38~50% and their values tended to increase with increasing the distance between PBDs.

서비스 품질과 고객만족이 재구매 의도에 미치는 영향

정용길,민병권 충남대학교 경상대학부설 경영경제연구소 1998 경영논집 Vol.14 No.2

본 연구는 서비스 품질의 개념화와 측정 및 전반적 서비스 품질과 고객만족이 재구매의도에 미치는 관계에 관하여 조사하고자 하는데 목적이 있다. 분석결과 서비스 품질은 다차원이 아닌 단일한 하나의 차원으로 묶이고 있는 것으로 나타났으며, 전반적 서비스 품질과 고객만족, 그리고 재구매의 도간의 관계에서는 전반적 서비스 품질이 고객만족과 재구매의도에 정(+)의 영향관계를 나타내는 것으로 분석되었으나, 고객만족이 재구매의도에 미치는 영향관계는 유의하지 않은 것으로 나타났다.

풍화암에 근입된 그라운드 앵커의 인발거동 연구

박병수,정길수,전상현,유남재 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.B

This study is an numerical study of predicting the behavior of anchor embedded in weathered rocks, subjected to uplift loads, about ultimate pullout capacity and the failure mechanism. Factors influencing the behavior of anchors were investigated by reviewing the data about in0situ anchor tests performing numerical modelling with changing the bondage length of anchor, diameter of anchor body and diameter of tenden, and by Correlations between those factors were evaluated to apply them to predict the behavior of anchors. As results of numerical analysis, a linear relationship between bondage length, diameter of anchor body and diameter of tenden with ultimate pullout capacity was obtained on the one hand, from the result of numerical analysis changing the Young's modulus of weathered rock, this parameter was found to inflence to load-displacement and ultimate pullout capacity within the range of 10%, which was mot so significant to affect.

鐵棒 1回, 2回 및 3回 뒤공중돌아내리기의 比較 分析

申榮吉,金柄斗,安禹洪,金正子,吳東燮,朴宇奎 慶北大學校 體育科學硏究所 1987 체육과학연구지 Vol.3 No.-

The purpose of this study was to offer gymnasts data for successfully performing triple back somersault dismount(TBSD) and for designing training programs to progress gymnasts to the advanced dismount skills from the horizontal bar through comparative analysis of selected biomechanical factors of single back somersault dismount(SBSD), double back somersault dismount(DBSD) and TBSD. The subjects employed were a total of 4 male middle and high school gymnasts aged between 15 and 16 years. A motion-picture camera, fliming at a nominal rate of 54 frames/s, was used to record the performance of subjects on each trial. This camera was placed at a distance of 15 m from the inward pole of horizontal bar with its optical axis at right angle to this pole. The results obtained are summarized as follows: The mean release angle was 80.5° for the SBSD, 77.3° for the DBSD and 71.3° for TBSD. There were significant differences between the SBSD and the TBSD(p<0.01), the DBSD and the TBSD(p<0.05) but no significant difference between the SBSD and the DBSD. The angular velocity at release was 4.533 ㎭/s for the SBSD, 5.338 ㎭/s for the DBSD and 6.020 ㎭/s for the TBSD. There was a significant difference among these velocities(p<0.05, p<0.01). The linear velocity at release was 5.458m/s for the SBSD, 5.750m/s for the DBSD and 6.083m/s for the TBSD. In this case, we had a significant difference only between the SBSD and the other two somersaults(p<0.05, p<0.01). The shoulder angle at release was 170.5° for the SBSD, 167.0° for the DBSD and 154.3° for the TBSD. There were significant differences between the SBSD and the TBSD(p<0.05), the DBSD and the TBSD(p<0.05) but no significant difference between the DBSD and the TBSD. The hip and knee angle at release were increased respectively by increasing the number of somersault but showed no significant difference among these angles. The mean flight time from release to landing for each somersault was calculated; it took the subjects 1.315s to perform the SBSD, 1.345s to perform the DBSD and 1.416s to perform the TBSD. There was a significant difference among these somersaults with respect to time(p<0.05, p<0.01). The mean maximum height was 3,633m for the SBSD, 3,720m for the DBSD and 3,780m for the TBSD. There was a significant difference only between the SBSD and the other two somersaults. The mean horizontal distance was decreased respectively by increasing the number of somersault but showed no significant difference among these somersaults with respect to distance. The smallest hip angle during flight in the SBSD was 115.3° at 0.317s after the subject left the bar, for the DBSD it was 48.2° at 0.621s while that of the TBSD was 32.3° at 1,102s after release. The relationship between the time the smallest hip angle observed and the total flight time was determined; it took 24.1% of the total flight time of the SBSD to reach the smallest hip angle. In the DBSD, it took 46.2% of the total flight time to reach for the smallest hip angle and in the TBSD 77.8% of the total flight time to reach the smallest hip angle. From the above results, the gymnast would need to (1) increase angular velocity before release by manipulating of body shape, (2) change the release angle and (3) stay tuck position longer by shortening as quickly as possible the angle of each body joint to perform successfully the TBSD. Also to be able to perform quadruple back somersault dismount, a gymnast would need flight time of a minimum 1,782s.

수평배수재 배열의 진공압밀효과에 대한 수치해석

박병수,정길수,이종호,유남재 강원대학교 산업기술연구소 2003 産業技術硏究 Vol.23 No.A

This paper is results of numerical works of investigating effects of horizontal drain arrangements on vacuum consolidation. Extensive numerical analyses were carried out to find the appropriate arrangements of horizontal dram of vacuum consolidation. Commercially available program of CRISP. well know-n to be good to modelling the behavior of clay- material, was used Cam-clay model, based on the Critical State of Soil Mechanics(CSSM), was used to simulate the geotechnical engineering behavior of clay. Model test results carried out previously in the laboratory w-ere compared with numerically estimated results and it was found that results about consolidational settlement with times were in good agreements. Based on this confirmation. parametric numerical study was performed to investigate effects of horizontal drain arrangements on vacuum consolidation with changing the vertical and horizontal spacings between drains for the given soil properties and vacuum. The effect of distance of drain located in top layer from the surface of the ground on the settlement due to vacuum was also investigated. As a results of numerical analyses. appropriate arrangements of horizontal drain to maximize the consolidation settlement due to vacuum were found. The mechanism of vacuum consolidation about the vacuum pressures being transferred to the effective stresses around drains was also evaluated.

풍화암에 근입된 그라운드 앵커의 인발거동 연구

박병수,정길수,전상현,유남재 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.A

This study is an numerical study of predicting the behavior of anchor embedded in weathered rocks, subjected to uplift loads, about ultimate pullout capacity and the failure mechanism. Factors influencing the behavior of anchors were investigated by reviewing the data about in-situ anchor tests performing numerical modelling with changing the bondage length of anchor, diameter of anchor body and diameter of tenden, and by Correlations between those factors were evaluated to apply them to predict the behavior of anchors. As results of numerical analysis, a linear relationship between bondage length, diameter of anchor body and diameter of tenden with ultimate pullout capacity was obtained on the one hand, from the result of numerical analysis changing the Young's modulus of weathered rock, this parameter was found to inflence to load-displacement and ultimate pullout capacity within the range of 10%, which was mot so significant to affect.

모래다짐말뚝과 널말뚝으로 처리된 연약점토지반의 거동

유남재,정길수,박병수,김경수 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.B

Centrifuge model experiments were performed to investigate the confining effects of the sheet piles, installed to the sides of soft clay ground treated with sand compaction piles, on the bearing capacity and concentration ratio of composite ground. For the given g-level in the centrifuge model tests, replacement ratio of SCP and the width of surcharge loads on the surface of ground with SCP, the confining effects of installing the sheet piles on the edges of SCP ground on the bearing capacity, change of stress concentration ratio and failure mechanism were investigated. Kaolin, one of typical clay mineral, and Jumunjin standard sand were used as a soft clay ground and sand compaction pile irrespectively. As results of experiments, lateral confining effect by inserting the model sheet piles fixed to the loading plate was observed. For the strip surcharge loading condition, the yielding stress intensity in the form of the strip surcharge loads tends to increase with increasing the embedded depth of sheet piles. The stress concentration ratio was found not to be influenced consistently with the embedded depth of sheet piles whereas the effect of stress intensity on stress concentration ratio shows the general trend that values of stress concentration ratio are relatively high at the initial stage of loading and tend to decrease and converge to the certain values. For the failure mechanism in the case of reinforced with sheet piles, displacement behavior related to the punching failure, settlement right beneath the loading plate occurred since the soil was confined with sheet piles, was observed.

교대말뚝기초의 측방유동에 관한 원심모형실험

최동혁,정길수,박병수,유남재 강원대학교 산업기술연구소 2005 産業技術硏究 Vol.25 No.B

This paper is an experimental result of investigating lateral soil movements at piled bridge abutments by using the centrifuge model facility. Three different centrifuge model experiments, changing the methods of ground improvement at bridge abutment on the soft clayey soil (no improvement, preconsolidation and plastic board drain (PBD), sand compaction pile (SCP) + PDB), were carried out to figure out which method is the most appropriate for resisting against the lateral soil movements. In the centrifuge modelling, construction process in field was reconstructed as close as possible. Displacements of abutment model, ground movement, vertical earth pressure, cone resistance after soil improvement and distribution of water content were monitored during and after centrifuge model tests. As results of centrifuge model experiments, preconsolidation method with PBD was found to be the most effective against the lateral soil movement by analyzing results about displacements of abutment model, ground movement and cone resistance. Increase of shear strength by preconsolidation method resulted in increasing the resistance against lateral soil movement effectively although SCP could mobilize the resistance against lateral soil movement. It was also found that installment with PBD beneath the backfill of bridge abutment induced effective drainage of excess pore water pressure during the consolidation by embanking at the back of the abutment and resulted in increasing the shear strength of clay soil foundation and eventually increasing the resistance of lateral soil movement against piles of bridge abutment.